Drag bucket dumping apparatus



Aug. 5, 1958 Filed Feb. 15, 1956 P. L. CIACCIO DRAG BUCKET DUMPING APPARATUS 4 Sheets-Sheet 1 INVEN'ToR.

PETER Cmcclo Aug. 5,'195'8 P. L. clAccro 2,846,101

DRAG BUCKET DUMPING APPARATUS Filed Feb. 15, me 4 sheets-sheet 2 INVENTOR. PETE/ L. (JI/accio A T TOENEY'- All@ 5 1.953 P. L.- clAcclo -I 2,846,101

I DRAG BUCKET DUMPING APPARATUS Filed Feb. 15, 1956 `4 Sheets-Sheet 4 .30 Ffa-.1o Fic. 9 11H7 United States Patent() Flexible Manufacturing Corporation, Los Angeles,-

Calif., a corporation of California Application February 15, 1956, Serial No. 565,562

18 Claims. (Cl. 214-740) This invention relates to sewer cleaning machines of the drag bucket type wherein portable derricks are set Vadjacent consecutive manholes in ra sewer line to be cleaned, and wherein a drag bucket is introduced into -the sewer line through one of the manholes, is advanced into and then drawn back through the section of the sewer line between the manholes with a dredging action, and is then hoisted through the manhole; swung to one side and dumped. The general object of the invention is `to provide in such an apparatus, a hoist having improved mechanism for effecting the lateral shifting and dumping yof the bucket.

In a drag bucket apparatus now in common use, the derrick is provided with an unloading swing boom to which the loaded bucket is hitched as it is elevated from the manhole, land which is then swung horizontally about a vertical axis to convey the bucket to position from which is can be dumped. Manual effort is required for swinging the loaded boom and for dumping the bucket at the end of its swing.

A primary object of the present 4invention is to substantially eliminate the need for such manual effort and to attain the horizontal swinging action and dumping in a semi-:automatic operation.

An important further object is to enable the execution of the entire lbucket unloading operation much more rapidly than has hitherto been possible, thereby substantially increasing the daily work output of the apparatus.

Another object, a contributing factor .to the attainment of the more rapid operation referred to above, is to provide 'a mechanism which will guide the movements of the bucket -in the swinging and dumping operations, largely eliminating the necessity for hand guiding, and correspondingly speeding up such operations.

An important feature of the invention is the provision of a boom which swings in a vertical plane on a horizontal axis, starting at an elevated position above the manhole where it grasps the bucket as the latter is hoisted out of the manhole, and swinging by gravity to a dumping position shifted horizontally from the manhole.

The dumping of a drag bucket is effected by spreading the lips which, when held together, constitute the bottom of the bucket. The lips are controlled Iby linkage which is hooked to the drag cable and constitutes the draft connection between the cable and bucket. Thus the lips are held closed by cable tension applied through the link age, and open by gravity (under the weight yof the contents of the bucket) when the cable tension is relaxed. This is a feature of existing drag buckets, but inthe apparatus embodying such buckets, it has always required the exercise of some skill `and the coordinated efforts of two men to swing the bucket carrying boom laterally to lthe dumping position while maintaining just sufficient tension on the cable to maintain the bucket lips closed without retarding the swinging operation. One of the objects of the present invention is to eliminate the need for such coordinated elort and skill and to utilize the restraining pull of the cable to control the horizontal ice , 2 swinging operation while automatically maintaining sufficient tension to hold the bucket lips closed until the dumping position is reached.

Another object is to provide means for automatically clasping the bucket to -the end of the swinging boom as `an incident of hoisting the bucket above the man hole. Accessory to this object, the invention provides means for holding the boom in an elevated 'position above the man hole, and provides, at the swinging end of the boom, la grapple which, in such elevated position of the boom, is positioned to automatically `receive the edge of the bucket as it is elevated.

Further objects of the invention will become apparent in ythe ensuing specification and appended drawings, wherein:

Fig. 1 is a perspective view of an unloading hoist mechanism embodying the invention;

Fig. 2 is a fragmentary detail side view of the boom control mechanism;

Fig. 3 is a detail sec-tional view -of the same taken on the line 3--3 of Fig. 2; V

Fig. 4 is a detail sectional view taken on the line 4 4 of Fig. 3;

Fig. 5 is a detail sideV view of the ygrapple unit in the position thereof in which it receives the upwardly moving bucket, a portion .of the grapple clevis being broken away to illustrate the jaw;

Fig. 6 is a side view of the grapple unit in the dumping position;

Fig. 7 is a transverse sectional view of the `grapple unit taken on the line 7-7 of Fig. 5. i

Fig. 8 is a side view of a modified form of the invention;

Fig. 9 is -a fragmentary front elevational view of the same; and

Fig. 10 is a detail sectional view thereof.

`Referring now to the drawings in detail, l have shown therein, `as an example of one form in which the invention may `be embodied, a drag bucket hoist embodying a derrick (indicated generally by the reference character A) having suitable mobile carriage mechanismA (not. shown) for transporting the same to the job site and having suitable adjustable supporting legs 10 for firmly supporting the derrickV on the paved surface adjacent the manhole; .including a drag bucket B which, in its position shown in Fig. l :and with the derrick properly supported as above stated, is centered directly over the manhole; including -a swinging boom C for swinging the bucket B horizontally to a dumping position at one side ofthe manhole, such position being indicated in dotted lines in Fig. 1; a grapple unit D for grasping the bucket as it is` hoisted out of the manhole and supporting the bucket at the end ofthe Kboom Cas the latter swings horizontally; and boom latching control mechanism which operates, in response to certain movements of boom C to control other movements thereof, in a semi-automatic manner which will be more fully explained hereinafter. At this time it lmay be briefly noted that mechanism E latches the boom C in its bucket coupling position shown in full linesand subsequently releases it for downward and lateral swinging movement in response to upward movement imparted to the boom by bucket B.`

A. Derrick mechanism The derrick A includes the adjustable supporting legs 10, a pair of uprights 11 which are rigidly secured to horizontal chassis members 12 of the mobile supporting carriage and may be braced thereto by diagonal braces 13; a. crown arch unit 14 securedto the upper endsk of uprights 11V and including a crown beam 15 and a transverse brace bar 16;.an overhead roller `16 over'which there is trained a drag cable 1.7'coming from a windlass' apparatus including a free spooling cable drum 18 and thence extending downwardly to the drag bucket B and a back lash pulley assembly 19, all of a conventional construction and arrangement as utilized, for example, in the power bucket machines illustrated in the catalog of Flexible Sewer-Rod Equipment Co., of Los Angeles, California.

In the present improvement, there is added to the derrick A a crane arm 21 secured, as by a clamp 21', to crown beam an upright bar 22 being secured, as by welding, to the outer end of arm 21 and secured and braced by a brace rod 21 secured to its upper end and extending back to arm 21 in triangular formation. Upright bar 22 forms a guide for a slide bracket 23 of channel section having in its web an adjustable longitudinal slot 24 through which there is extended a threaded stud 25 securely anchored to guide bar 22, a nut 26 being threaded on stud 25 to secure slide bracket 23 in any position of vertical adjustment thereof that may be selected.

Slide bracket 23 provides a vertically adjustable support for a pivot 27 consisting in a tubular eye on the end of a hinge leaf 28, and a bolt 29 extending through such eye and through a pair of lingers 30 consisting in integral extensions of the lower end of slide bracket 23. Hinge leaf 28 is secured, as by welding, to the upper end of boom C.

It will now be apparent that arm 21, slide bracket 23 and pivot Z7 provide a vertically adjustable pivotal support for the upper end of boom C at a position in front of and spaced horizontally from the plane of derrick supports 11, such that the boom C may normally assume a position inclined downwardly and horizontally toward such supports to clasp the bucket B as it is hoisted out of the manhole. When released for free swinging movement, boom C will swing by gravity under the weight of the loaded bucket, to the dumping position in which it extends vertically downwardly as indicated in the dotted lines. Thus the lateral swinging of the boom supported bucket to its dumping position is energized by the weight of the bucket and requires no manual elort.

B. The drag bucket The drag bucket B is of conventional construction, embodying a cylindrical tubular body 31, a pair of clam shell type lips 32 hinged at 33 to diametrically opposite sides thereof, and a pair of operator slides 34, each having a longitudinal slidable connection with bucket body 31, each having at lower end a pair of pivotal connections to adjacent lateral corners of respective lips 32, and each having at its upper end an aperture into which is pivotally hooked the respective ends of a supporting bail 36, and at its lower end an aperture into which is pivotally hooked a lower bail 36', connected to a cable section 17'. The terminal portions of the cable sections 17 and 17 may be attached to bails 36, 36 by suitable connectors 37.

The above described bucket construction is in itself conventional, but is combined with other features of the present invention to provide the semi-automatic operation which will be described more in detail hereinafter. It may be noted that in the operation of the bucket, the swinging of the bucket from above the manhole to its dumping position may be controlled by playing out the cable 17 while maintaining sucient restraining tension therein (transmitted to lips 32 through slides 34) to maintain the lips 32 closed until the bucket reaches the dumping position, whereupon, by slackening the cable 17, the lips 32 will swing downwardly around their pivots 33, drawing slides 34 downwardly. Thus opened, the bucket will discharge its contents and the cable 17 then may be rewound on drum 18 to draw the bucket back to the position above the manhole, the renewed cable tension causing the lips 32 to again close.

4 C. Swinging boom Boom C comprises a main arm 40 secured at its upper end to hinge leaf 28, a lateral arm 41 welded to the upper end of arm 40 and normally projecting therefrom toward derrick A at an angle of somewhat less than and a brace 42 the ends of which are welded respectively to the lateral arm 41 and to the main arm 40 near the lower end of the latter, to provide a triangular boom structure. Parts 40, 41 and 42 are preferably of tubular form, arm 41 having an open end in which is adjustably mounted a latching linger 43. A set screw 44 is utilized t0 secure linger 43 in a position where a suitable length thereof projects from arm 41. Finger 43 is engaged by latch mechanism E to support boom 40 in its raised, full line position of Fig. l.

Secured to the lower end of arm 40 is a flat end fitting 45 which supports a pivot bolt 46 to which grapple D is pivoted.

Secured to hinge leaf 28, as by welding, is a knuckle tting 47 of sleeve form, in which is mounted the shank 48 of a latch actuator wand 49. Wand 49 is bent at an obtuse angle to its shank 48 (the latter being normal to the plane of boom members 40, 41, 42) and subtends an acute angle to said boom plane, such that wand 49 may engage near the outer end of the latch control trigger lever hereinafter described. Wand 49 projects generally toward the derrick A, and, in the raised, full line position of boom C, is inclined upwardly above the latching mechanism E as shown in Fig, l. As the boom C swings to the bucket dumping position, wand 49 correspondingly swings downwardly to the position shown in dotted lines, wherein it engages and actuates the latch mechanism E as hereinafter explained. Shank 48 is xedly secured in knuckle fitting 47 by means of a set screw 50 which may be loosened to adjust the angle between wand 49 and boom arm 41.

D. Grapple unit Grapple unit D comprises a clevis 51 which embodies opposed fingers 52 and 53, the latter comprising a pair of flat, parallel cheeks that are spaced to provide a slot 54 for receiving a pivoted gripping jaw 55; the cheeks are joined, at the lower end of linger 53, by an integral web 56 which extends at an acute angle (in the range between 30 and 45) to the longitudinal axis of finger 53. Fingers 53 and 52 are integrally joined by a pair of bridges 57, formed as integral continuations of the cheek portions of finger 53, and similarly spaced. Bridges 57 are projected to provide a pair of spaced ears which receive the flat end fitting 45 of boom arm 40 and are pivotally connected thereto by the pivot bolt 46 extending through registering apertures in the bridge ears 57 and tting 45.

Iaw 55 is of segment shape, having a relatively wide end 58 of arcuate contour and serrated to provide teeth 59 for gripping engagement with the outer face of bucket body 31. The lower corner of arcuate end 58 is pivoted to finger 53 by a pivot bolt 60 extending therethrough and through registering apertures in cheek portions of finger 53. From pivot 60, the arcuate array of teeth 59 extends upwardly and around the pivot axis with a continuously increasing radius, and in a path which may be approximately spiral with reference to the pivot axis. The heel portion of arcuate end face 58, radially opposite pivot 60, in the open position of the jaw shown in Fig. 5 is substantially tangent to the near side of slot 61 that is defined between fingers 52, 53 and parallel to the opposite side of slot 61. The curvature of end 58 is such that, as jaw 55 is tilted clockwise (as viewed in Figs. 5 and 6), the point of tangency between arcuate end 58 and the line parallel to the opposite side of slot 61 will progressively shift upwardly. This point of tangency determines the center of pressure engagement of teeth 59 against the outer surface of the section of bucket body 31 received 'in slot 61, with the inner surface of the bucket body engaged against the linger 52 at the opposite side of slot 61, and may vary to accommodate any variations in thickness of bucket bodies. The teeth 59v are of saw-tooth form and' are inclined upwardly to attain maximum penetration of bucket body 31 in response to the downward pull of the bucket body under the weight of its contents, whereby the grasp of the bucket by the grapple is automatically tightened by the downward pull of the bucket. A major factor in the automatic tightening of the grapple on the bucket, however, is the actuator linkage which will not be described.

'I'he end of jaw 55 opposite arcuate end 58, which may be tapered as shown and which functions as a lever, is provided with an aperture in which is hooked a transverse trunnion end portion 62 of a link 63, thus providing a pivotal connection. Link 63' extends upwardly and is pivotally connected by means of a transverse trunnion end portion 64 thereof, in an opening in an ear at one end of a clamp 65 which is clamped, by means of a clamping bolt 66, upon boom arm 40 above fitting 45. Pivots 46, 60, 62 and 64 are arranged in trapezoidal array such that when grapple clevis 51 is moved on its pivot 26, as indicated by arrow 67, in the direction of alignment with boom arm 40, the consequent elongation in the distance between pivots 60 and 64 will result in the above mentioned clockwise pivotal movement of jaw 55 about its pivot 60, transmitted thereto by link 63, with the result that teeth 59 will advance into slot 61 and grip the wall of a bucket body 31 previously loosely received by the grapple.

The above mentioned movement of grapple clevis 61 relative to boom arm 40, in the aligning direction 55, results automatically from the action of bucket B, in response to gravity, tending to maintain a pending position with its major axis vertical, as opposed to thel action of clevis 51 in tilting the bucket toward the inclined position shown in dotted lines in Fig. l, as the boom C swings from they coupling position shown in full lines toward the unloading position shown in dotted lines. It will' now be apparent that, in this swinging movement of the bucket as coupled to the boom, a tilting couple will be applied to grapple clevis 51 by the bucket, tending to widen the angle between the longitudinal axes of arm 40 and clevis 51 toward an alignment position, and the force of this couple, which is resolved into clamping pressure of teeth 59 against the bucket body 31, will continuously increase to a maximum at the end of the swing. This is important for the reason that, when the bucket reaches the unloading position, the cable 17 is relaxed so as to permit the slide bars 34 to shift downwardly and the clamp lips 32 to swing outwardly for discharging the contents of the bucket. During this unloading of the bucket, the full weight of the bucket is supported by grapple unit D. Conversely, as the bucket is drawn back to the coupling position, under the pull of cable 17 as it is rewound on drum 18, the grip of jaws 55 against the bucket body 31 will gradually relax until, in the position of boom C shown in full lines of Fig. l, the bucket, still received in clevis 51, and hanging vertically, will have tilted the clevis 51 in a counterclockwise direction, as viewed in Fig. 5, so as to restore it to its original angularity with reference to the boom 40, thus actuating the jaw 55 through linkage 53 to release its grip on bucket body 31.

E. Latchz'ng mechanism As previously noted, latching mechanism E functions to normally latch boom C in the raised, coupling position until the bucket is hoisted and coupled to grapple unit D, and thereupon operates to release the boom C for downward and lateral swinging movement, guiding the bucket to the dumping position.

To this end, latching mechanism E comprises a bracket 70 attached as by bolt 71, to the underside of crane arm 21, and including an integral bearing sleeve 72 which projects downwardly,F also a pair of opposed bosses'A'S on opposite sides of sleevek 72, in which are anchored the aligned shank portion 74 cf a pair of spring latching jaws 75. Jaws 75 project downwardly, are bent inwardly to provide converging lower portions 76, are further bent inwardly to provide aligned seats 77 at the lower ends of converging portions 76, and are then bent outwardly to provide downwardly diverging pilots 78 which, where they join seats 77, normally define a narrow pass 79, ,through which latch finger 43 of boom arm 41 can be forced upwardly with a camming action against pilot 78 which spreads the spring jaws 75` as indicated in dotted lines in Fig. 3. As the finger 43 clears the pass 79, jaws 75 will close by spring action, thus engaging the seat 77 beneath the linger 43 to support the boom C in its raised, coupled position.

Jaws 75 are formed, at the bends between their upper portions and converging lower portions 76 with eyes 80 through which are extended pivot bushings 81, eachbushing 81 receiving a bolt 824 which passes through an outer end of a respective toggle link 83 and isv anchored thereto, as by means of a nut 84 which clamps the link 83 tightly against the end of sleeve 81, with the latter in turn clamped against a washer 85 which is seated against the head of bolt 82. The inner bands of toggle links 83 are pivotally connected to one another by a pivot stud 86 which extends through both links 83 and is anchored in a boss 87 functioning as the head thereof'. Secured in boss 87 and projecting radially therefrom isone end of a guide stem 88 which is slidably received in a bearing bore in bracket sleeve 72. Secured to the lower side of boss 87 is a saddle element 89 of dihedral obtuse angular form, flaring downwardly so as to receive and center the latch linger 43 as the latter moves upwardly through pass 79. In the normal position of the variousv parts of the latch unit E, jaws 75 are closed, toggle links 83 are broken downwardly, and saddle element 89 is spaced above seats 77 just sufficiently to receive latch linger 43 therebetween. Further upward movement of finger 43 above seat 77 will transmit, through saddle 89, upward pressure to the pivotal connection between toggle arms 83, straightening the arms 83 to any aligned, on-center position and shifting them slightly above this position (above center). At this point, boss 87 will' engage the lower end of guide sleeve 72 to limit the upward movement at a position just suiiciently above` center to cause the toggle arms 83 to lock with the jaws 75 spread apart so that latch finger 43 may freely move downwardly through the now widened pass 79.

The toggle linkage (under the yielding pressure of spring jaws 75) will remain locked in the latch opening position just described, until positively actuatedy back to the normal position in which the jawsv 75 reclose. This is provided for' by engagement of actuator wand 49 against a trigger lever 90 which is securely anchored to toggle link 83', as by having its shank end secured in a boss 91 which in turn is secured at one end to an ear` 92 formed as a laterally bent extension of the inner end of link 83 (Fig. 4).

Operation The operations ofthe various units of the mechanisml have been described in connection with the description of parts of such units and their relationship, and reference is made to the foregoing description for detailed aspects of the functioning of the separate units. The present explanation therefore aims to correlate the operation of the various units into a unified Whole.

In the drag bucket cleaning of an underground sewer line, duplicate portable cable operating machines (hoists) are installed at diierent manholes along the sewer line, the two hoists facing one another, the cable 17, 17' extending downwardly through one manhole, around suitable guide pulleys at thebottom thereof, thence horizontally through the sewer line and thence upwardly around similar guide pulleys and 'out through the other manhole.

Bail 36, hooked to the upper end of bucket B, is opposed to bail 36' which is hooked to the lower ends of slide bars 34 and is attached to the other section 17 of the cable. This other section 17 has its remote end wound upon the drum 18 oif the machine which is remote from the one shown in Fig. 1. Assuming that the bucket B as shown in Fig. l has just been released by grapple unit D, the remote machine will be operated to tension cable section 17 and draw the bucket downwardly into the near manhole (this action positively opening the lips 32) and the bucket is then drawn lengthwise through the sewer line so as to dredge accumulated dirt and debris therefrom.

The cable section 17 shown in Fig. 1 is played out during this movement. At a proper point, as judged by the experience of the operator, the movement is reversed, cable section 17 being wound upon drum 18 `of Fig. l and the other cable section being relaxed and allowed to follow while the bucket is returned to the near manhole, completing the filling of the bucket, and the bucket is then hoisted through the manhole and returned to the coupling position shown in Fig. l. This reversal of movement will have closed lips 32 at the beginning of the return movement of the bucket, and the lips will remain closed as the bucket is hoisted to the coupling position.

With the latch finger 43 resting upon seats 77 of latch unit E, grapple unit D will be disposed in the proper position to receive the upper end portion of bucket body 31. The edge of the bucket is guided into slot 61 by the inclined lips 69 of fingers 52, S3 and rises in slot 61 until it engages the upper end thereof. lifted a further distance sufficient to swing boom C upwardly to the point where latch finger 43 has engaged saddle element 89 and has shifted the toggle links `83, 83 upwardly to the above center, locked position shown in dotted lines in Fig. 3, thereby spreading jaws 7S to their open positions shown in dotted lines and holding them in spread position until the toggle linkage is subsequently unlocked. The operator then plays kout the cable section 17 so as to allow the bucket and boom C to swing downwardly in unison, sufficient restraining pull on the cable 17 being maintained to maintain the bucket against the upper end of the grapple slot 61. Actually, it is only necessary to restrain the cable sufciently to avoid devellopment of slack therein as the bucket and boom swing downwardly, and thus it is possible to allow a substantially tfree swing and to take advantage of momentum in carrying the bucket to a maximum distance horizontally from the manhole. As the swing progresses, the bucket will be forced by grapple D to tilt upwardly from its originally vertical position to substantially match the angular shifting of boom C, but the gravity resistance of the bucket to being thus tipped upwardly will cause the grapple clevis 51 to shift somewhat toward a position of alignment with arm 40 (e. g. from starting position shown in Fig. to the shifted position shown in Fig. 6) thereby actuating the jaw 55 to securely grip the bucket body as the swing progresses.

At the end of the swing, with the boom C in a substantially depending position as indicated in dotted lines in Fig. 1, the cable section 17 is relaxed to the point where the weight of lips 32 under the bucket contents, assisted by the weight of the slide bars 34 and parts 36 and 37, will shift slide bars 34 downwardly and lips 32 will swing to their open positions, discharging the contents of the bucket at one side of the manhole.

As the boom C swings downwardly, actuator wand 39 will correspondingly swing downwardly from its full line position toward its position shown in dotted lines in Fig. 1, and toward the end of the swing, will engage trigger lever 90, which at this point is inclined slightly upwardly from the horizontal to correspond to the inclination of link 83 in its dotted line position of Fig. 3. In the final stage of downward movement of Wand 49 it presses the trigger lever downwardly until the toggle links 83, 83' have passed below the on-center position, whereupon the toggle linkage and trigger 90 will drop back to their nor- The bucket is then n mal positions shown in full lines both in Fig. l and in Fig. 3. This operation recloses the jaws 75, setting the latch mechanism E for latching engagement of latch nger 43.

At the end of the unloading operation, the operator operates the machine to wind cable section 17 on drum 18, drawing the bucket B back toward derrick A, the boom C following, until the parts return to the position at which the bucket was initially coupled to grapple D. In the terminal stage of this movement, latch finger 43 will pass upwardly between pilots 78, exerting a wedging action against the pilots for spreading the jaws 7S just sufticiently to permit the finger 43 to move through pass 79, whereupon the jaws will reclose by spring action, the seats 77 engaging beneath nger 43 to support the boom C in the coupling position. In returning to this position, the bucket B, assuming a vertically depending position by the operation of gravity, shifts the grapple clevis S1, with reference to arm 40, in a clockwise direction as viewed in Figs. 4 and 5, restoring it substantially to the position shown in Fig. 5 in which jaw 55 has been actuated by link 63 to release its grip on bucket body 31. The bucket A may now be lowered, leaving the grapple D suspended in the coupling position in which it is again engaged by the bucket when the latter is drawn from the manhole with another load therein. The bucket is now lowered into the manhole to receive the subsequent load of material, thus completing the cycle of operation.

The operation is particularly characterized by the fact that the entire cycle of operation of the apparatus can be controlled by operators operating the two sections of the cable in unison so as to alternately draw the bucket into the sewer line, then return it to the hoisted coupling position, then move it through the various stages of unloading, and then return it to the sewer without touching the bucket.

The invention as disclosed in F gs 8-10, preferred form Figs. 8-10 disclose the invention in a preferred form embodying certain improvements which will now be described, the apparatus being otherwise the same as that disclosed in Figs. 1 8, inclusive.

in this improved form the arm 21a is horizontal and brace 21 is inclined downwardly from head 22 to derrick A. Boom C, instead of having a fixed axis connection to pivot 27, is provided with an elongated clevis loop 94, defining a slot 9S, through which pivot bolt 27 extends. Normally, boom C hangs with the closed upper end 96 of loop 94 bearing against pivot bolt 27.

Instead of the rigidly braced connection of arm 41 to boom shaft 40, a modified arm 41a is formed with an elbow portion 97 having at its end an eye 93 connected to shaft 49 by a pivot bolt 99 supported in a clevis 100 on shaft 4h. A coil spring 101, connected under tension between elbow 97 and the upper end of shaft 40, yieldingly maintains elbow 97 normally in abutting engagement with a stop 102 secured to shaft 40, thus determining the correct operating position of arm 41a in relation to shaft 40. The pull of spring 101 is sufticiently strong to maintain this relationship while arm 41a is forced between latching shoulders 77. However, if the operator should carelessly elevate drag bucket B higher than its specified upper limit of elevation after having engaged its upper edge in grapple D, shaft 40 and arm 41a will execute yielding actions such as to avoid being damaged from being forced beyond their normal upper limit positions. Arm 41a, upon meeting unyielding resistance from saddle 89 after having engaged the latter and having moved it to its upper limit position stopped against bearing sleeve 72 (Fig. 3) will move no further, even though the swinging end of boom C is further elevated by the bucket. Instead of being bent by such further elevation of the boom, arm 41a will yield a pivot 99, spring 101 elongating so as to allow shaft 40 to move closer to arm 41a, and elbow 97 moving.

.uponshaft -40A along itsllongitudinal'axis. To avoid .buckling of the shaft in such event, the upper end of .Ztheshaft simply slides iupwardly while folding toward arm 41a at pivot 99.

:I claim:

f 1. Apparatus` for unloading acable-suspended drag Vbucket having an openable bottom maintained closed "by cable tension, comprising: a derrick having at its upper end means for. suspending-a lengthof cable for hoisting. said bucket vfroma :tilling position; a crane arm secured to said upper end ofthe derrick and project- `ing horizontally; agrapple adapted to receive and to ,grasp an upper edge portion of said bucket; a boom having afree end carrying saidn grappleand a pivot suspending Vits other end from` the outer end of said crane arm for lateral swinging movement respectively `aw`ayi`from 'the derrick to an unloading position freehanging from said pivotl from a couplingposition inclined -`dwnwardly'and. toward 4the`derrick with said grapple 'elevated above 'its' free hanging, position and 4adjacent `thetderrick to receive said` upper edge portion of the bucket as the latter is"hoisted from said iilling position;` a latch means carried'by'said' crane arm and operable to make "latching 'connection with Vsaid boom as the latter is swung upwardly to said coupling' position and to `support the "rbo'o'm'insaid coupling position, said'latching means being i further operable to release said boom 'foi-"gravity swinging movement Ifrom said couplingposition to said unloading position "12.Appar'atus 'fort unloading a cable-suspended drag -buckethaving'an 'openable bottom maintainedV closed by cable tension, comprising: a' derrick having at'its upper -erid1means" `for suspending a llength of cable for'hoisting lsaid'bucketWfrom a'lling positioma crane arm' secured tosaid'upper end of the derrick and 'projecting hori- 'zontally;`a1grapple adapted toreceive andto'grasp an 2upper edgeportion of said bucketya boomhaving a free 'endcarrying' `said grapple and a pivot suspending its other endf-from`theouter end'of'v'said crane armfor lupward and downward swinging movement respectively toward and from the derrick between an unloading position freehanging from said pivot and a coupling position inclined toward the Vderrick with said grapple elevatedlabove its free-hanging position and adjacent-the derrick to receive -said upper edge portion of the` bucketas the latter is .hoistedfrom said-'filling apparatus position; said boom beinglof triangular formand including a -main'arm extendingfrom said pivot to said grapple and a latching arm extending laterally from said main arm in a direction to lie beneath and adjacent said crane arm when the boom is in said coupling position; and latching means carried by said crane arm intermediate said pivot and the derrick, projecting downwardly from said crane arm and operable to receive and automatically make latching connection with said latching arm as the boom is swung upwardly to said coupling position, and to support the boom in said coupling position, said latching means being further operable to release said latching arm so as to cause the boom to swing by gravity from said coupling position to said unloading position. 3. Apparatus as defined in claim l, wherein said latching means comprises a pair of opposed spring jaws arranged to receive said latching arm as the latter moves upwardly, to yield apart under upward pressure thereof, and to close therebeneath to effect said latching connection, and including spreader means bridging between said spring position thereon-and operable, in'response to upwa'rd pressure therefrom,`to spread ysaid jawsY for release'of Isaid latching arm upon`downward"return-movement thereof, whereby to-initiate said gravity s'winginglmo've- 'ment of the boom.

4. Apparatus as `dened in claim 3, 1whereins'aid Vbridging spreader means comprises toggle links vhaving outer ends pivoted to the respective spring-jaws-and'i'niier ends pivotally connected and arranged to' yieldup'wa'rdly under pressure from said latching arm, 'tot an abovecenter position in which said spring jaws-are `sp`read and said toggle links are locked 'against downward return movement, and meansfor limitingupward 'movementI of said toggle links beyond saidabove-center position.

5. Apparatus as dened in claim 4, including a saddle fitting carried by said pivotally Connected innerendsl-of the toggle links, and' guide means positioning saidsaddle it'ting toV receive the pressure ofsaid-latchingv arm and transmit the same to said toggle links.

6. Apparatus as denedin claim 5, wherein saidi-guide means comprises a stem secured to said saddle Afitting and a guide bushing attached to said crane arm,' lin ing saidgrapple and a pivot suspending its other endtrom the outer end of said crane arm for upward andf' downward swinging movement "respectively t toward'v andl'from the derrick between an unloading position free-hanging from said pivot and a coupling position inclined toward the derrick with said grapple elevated above its free" hanging position and adjacent the derrick to receive said-upper edge portion of the bucket as the latter -is hoisted from said filling position; said boom having a latching 'arm positioned to lie beneath and generally parallel to said crane arm when the boom` is' in said `couplingt'position; and'latching means comprising a pair of opposedlspring jaws arranged to receive said latching arm as the ylatter moves upwardly, to yield -apart under upward pressure thereof, and to close therebeneath to effectsaidV latching connection, a pair of toggle links having'outer'ends pivoted to the respective spring jaws and "innerends pivotallyl joined and arranged to yield upwardly under'pressure from said latching arm, to a slightly above-center position in which said spring jaws are spread so asto release said latching-arm and said togglelinks'are locked -against downward return movement; meansfor'- limiting upward movement of said toggle linksbeyond saidabovecenter position; a trigger rod secured to one of said toggle links and projecting beyond its pivotal connection to the other toggle link; and an unlatching wand secured to said boom and positioned to engage said trigger rod as the boom approaches said unloading position, and to shift said toggle links below an on-center position, whereby to cause said latch jaws to re-close by spring action.

8. Apparatus as dened in claim 7, wherein said unlatching wand is flexible for yielding action so as to allow the boom to swing beyond the point of reclosing of the latch jaws.

9. Apparatus for unloading a cable-suspended drag bucket having an openable bottom maintained closed by cable tension, comprising: a derrick having at its upper end means for suspending a length of cable for hoisting said bucket from a lling position and a boom support disposed in laterally spaced relation to said cable suspending means; a grapple adapted to receive and to grasp an upper edge portion of said bucket; and a boom having a free end carrying said grapple and a pivot connecting its other end to the outer end of said boom support for swinging movement toward and from the derrick between an unloading position free-hanging from said pivot and a coupling position inclined toward the derrick with said grapple elevated above its free-hanging position and adjacent the derrick to receive said upper edge portion of the bucket `as the latter is hoisted from said iilling position; said grapple comprising a clevis pivoted to the boom and arranged to receive an upper edge portion of the bucket, a jaw pivoted to saidclevis and cooperable therewith to grip the said edge portion, and linkage connecting said jaw to the boom in a manner to limit the pivotal movement of the clevis relative to the boom so as to lock the bucket to the boom in iiXed angular relation thereto, so as to transmit from the boom to the bucket as the two swing toward the unloading position, tilting movement displacing the bucket from a free-hanging position to one inclined from the vertical, and simultaneously to load the jaw with a couple derived from the weight of the bucket as thus displaced, such as to clamp the jaw against the bucket.

l0. Apparatus as deiined in claim 9, wherein said clevis comprises opposed parallel fingers one of which comprises laterally `spaced cheeks defining between them a slot in which the jaw is received.

11. Apparatus as defined in claim 10, wherein said jaw is of segmental marginal contour, having an arcuate wide end that is serrated to provide gripping teeth and a narrowed opposite end projecting from the clevis and attached to said linkage.

l2. Apparatus as' defined in claim 1l, wherein said linkage comprises a bar link pivoted at one end to said narrowed end ofthe jaw and at its other end pivotally connected to the boom, said boom, clevis, jaw and bar link being arranged in trapezoidal array such that pivotal movement of the clevis in which it moves toward alignment with the boom, will cause said clamping movement of the jaw.

13. Apparatus as dened in claim 12, wherein said clevis has a slot for receiving said bucket edge portion, and wherein said arcuate end of the jaw has an outer corner pivoted to said one finger and normally substantially tangent to the near side of said slot, and an inner corner portion that shifts toward said slot as said jaw pivots in the clamping direction, and wherein tangency of said arcuate end gradually shifts toward said innercorner portion as the jaw thus pivots.

14. Apparatus as defined in claim 13, including a clamp attached to said boom and carrying the pivot that connects said bar link to the boom, said clamp being adjustable longitudinally of the boom to adjust the clamping action of said jaw.

15. Apparatus for unloading a cable-suspended drag bucket having an openable bottom maintained closed by cable tension, comprising: a derrick having at its upper end means for suspending a length of cable for hoisting said bucket from a filling position and a boom support disposed in laterally spaced relation to said cable suspending means; a grapple adapted to receive and to grasp an upper edge portion of said bucket; a boom having a free end carrying said grapple and a pivot suspending its other end from said boom support for lateral swinging movement respectively toward and from the derrick to an unloading position free-hanging from said pivot from a coupling position inclined downwardly and toward the derrick with said grapple elevated above its free hanging position and adjacent the derrick to receive said upper edge portion of the bucket as the-latter is hoisted from said filling position; a latch means carried by said derrick and operable to make latching connection with said boom as the latter is swung upwardly to said coupling position and to support the boom in said coupling position, said latching means being further operable to release said boom for gravity swinging movement from said coupling position to said unloading position.

16. Apparatus as defined in claim 15, wherein said boom has at its upper end an elongated loop in which its suspending pivot is received, said loop providing for upward lost motion of said boom at said pivot at the end of its upward swing in the event the drag bucket is over-hoisted beyond its prescribed upper limit position.

17. Apparatus as defined in claim 15, and including a latching arm pivotally connected to said boom and positioned for engagement by said latching means, and including spring means connecting said latching arm to the boom in a manner to normally maintain a correct operating position of said latching arm relative to said boom, but yielding to allow the latching arm to yield toward the boom in the event the latter is hoisted beyond its prescribed upper limit position.

18. Apparatus as defined in claim 15, wherein said boom has at its upper end an elongated loop in which its suspending pivot is received, said loop providing for upward lost motion of said boom at said pivot at the end of its upward swing in the event the drag bucket is over-hoisted beyond its prescribed upper limit position, and including a latching arm pivotally connected to said boom, and including spring means connecting said latching arm to the boom in a manner to normally maintain a correct operating position of said latching arm relative to said boom, but yielding to allow the latching arm to yield toward the boom in the event of said over-hoisting.

References Cited in the tile of this patent UNITED STATES PATENTS 715,228 Wilcox Dec. 2, 1902 955,812 Kuhlman Apr. 19, 1910 1,234,717 Beindorf July 31, 1917 2,417,121 Nelson Mar. 11, 1947 2,502,593 Robinson et al. Apr. 4, 1950 

